1. Field of the Invention
The present invention relates to a new pacemaker which reestablishes or keeps the physiological electric synchrony of the heart and a method of application in the right ventricular septum, being possible to use, in order to facilitate the implantation and to avoid the connection and disconnection, a sheath to check a proper place and then screw the catheter in said place.
This method together with the pacemaker are responsible for the reestablishment and preservation of the physiological electric synchrony of the heart and is herein referred to as “EB (Electric Bypass)” due to the obtention of an alternative electric circuit and to the creation of the virtual electrode.
With the pacemaker of my invention and its method of application, a septal ventricular stimulation system with a high performance electrical and contractile synchrony is produced, thus significantly changing the implantation of a definitive pacemaker, making them more physiological. In the examples where my invention was applied, several patients with QRS narrowing were tested as well as those suffering disorders in the AV atrio-ventricular and intraventricular impulse conduction. The results show the QRS narrowing phenomena and the orientation of the depolarization with similar vectors compared to those of a depolarization by the His-Purkinje system.
2. Description of the Prior Art
A pacemaker is an electronic apparatus that produces electric impulses, intended to stimulate the cardiac muscle. The number of impulses produced per minute is called frequency. The mechanism is fed from electric power from batteries. These electric impulses are conducted to the heart by means of a cable (or electrode), so that the pacemaker itself (or pulse generator) is placed at a quite shallow surface underneath the skin, while the electrode is placed much more deeply inside the organism, up to the heart.
The first pacemakers, asynchronous, were only blind instruments that continuously produced 70 electric impulses per minute, carrying them up to the heart by means of an electrode. The electronic circuit consisted of a few diodes, transistors, resistors and a capacitor. One or more batteries provided the necessary power to feed the circuit and stimulate the heart. These pacemakers complied very well with their role when the patient's own rhythm was absolutely absent. However when the failure in the rhythm was just intermittent, the pacemaker slightly interfered with the normal rhythm, at the moments when it was reestablished.
Afterwards, the more intelligent pacemakers came out, Pacemakers on demand, that stopped functioning when the cardiac rhythm was reestablished. This supposed the introduction of new circuits, capable of detecting the electronic activity of the heart and new pacemakers were called “on demand” since they just started working when they were necessary.
Pacemakers on demand may be implanted in the atrium, in order to treat failures in the sinus node; or in the ventricle so as to treat the heart block.
An important advance in the development of programmable pacemakers was to make them more versatile. The first ones only worked under a frequency set in factory, with fixed pulse energy and were able to detect certain level of cardiac electric activity also fixed.
It may be interesting to be able to change the stimulation frequency at certain moments, adjusting it to the organic needs. In other cases, a decrease in the pulse energy may be advantageous to save power and extend the duration of the pacemaker, or on the contrary, increase it if the muscle became resistant. In some patients, it would be useful to get the pacemaker to have higher or lower capacity for detecting electric impulses, in order to eliminate the influence of abnormal rhythms, or external interferences. All of the above-mentioned options became possible with the introduction of the Programmable Pacemaker.
Currently, different kinds of these pacemakers are available, which allow the adjustment of their function to different states of healthy or sick organism without causing any discomfort to the patient.
Programmable pacemakers are insensitive to the needs of the organism and their functioning is to be changed from the outside, so that their adaptability is relative. There are other kinds of pacemakers which are more physiological, that is to say, more capable of meeting the organic needs at every moment, with its continues fluctuation. In cases where the formation of the cardiac stimulus in the atria is maintained, and the problem lies on the conduction block between the atria and the ventricles, a kind of pacemaker which senses atrial activity and then stimulates the ventricles can be introduced. These are the “atrial triggered” pacemakers, which constitute a practical reality, once the problems of implanting two catheters, one in the auricle and the other in the ventricle, are solved. In these pacemakers, as the variations in the atrial rhythm depend on organic needs variations, the pacemaker is led by the body needs
Currently, for cases where it is not possible to use atrial guidance, pacemakers have been developed that are capable of sensing other parameters in the body activity, changing automatically their frequency (self-programming frequency pacemakers). Some pacemakers catch vibrations of the body during movement; others detect breathing activity and accelerate frequency of the heart in combination with the frequency of breathing; others detect fine vibrations in the cardiac electric activity caused by exercise and others being at the stage of design or project respond to the exhaustion of oxygen in blood, to changes in body temperature, or even to many of these causes.
First pacemakers were big and short-lasting. They weighted one hundred grams, had a diameter of 7-8 cm, and 2-3 cm of thickness, wrapped with silicone rubber toughly applied. They were fed by mercury-zinc batteries that could last no more than 2-3 years. Electrodes broke frequently because of the phenomenon called “fatigue of materials”.
Nowadays, size has been reduced by a quarter or a fifth, weight has been reduced to less than a third, duration reaches 5-10 years according to the designs, and electrodes are made of a certain design and material that practically prevent their breaking and allow energy savings.
At present, we have smaller pacemakers, more powerful, long lasting, more versatile and more comfortable for the patient.
Traditional ventricular stimulation in the apex of the right ventricle (RV) is well known in the art, which through several years of use, it has shown an important reliance as regards permanence of the catheter in the correct place, control of the cardiac frequency and facility for its implantation. FIG. 9 illustrates a chart that shows right ventricular stimulation, “Standard Bipolar Stimulation on apex of RV”. However, day after day it is proven that regardless of the fact that it keeps atrio-ventricular synchrony through stimulation of both chambers, results are far away from causing a real physiological synchrony. Right ventricular stimulation on the apex of RV generates a pattern of electric activation, asynchronous in itself and therefore asynchronous left ventricular contraction.
On the other hand, stimulation in the apex of the RV can lead to non-homogenous left ventricular contraction, myofibril erradication, and disorders of myocardic perfussion. This generates an increase in the morbidity and mortality of these patients, therefore leading from several years ago to look for other places of unique and simultaneous stimulation in order to improve electric and hemodynamic parameters of permanent stimulation.
As it can be seen novelty in pacemakers was only slightly related to the place of application of electrodes. In the new pacemaker of my invention, it can be seen as an advantage, apart from those described in the previous art, when applied on patients with pacemaker indication with preserved interventricular contraction, it prevents from deleterious effects of the traditional pacemaker over the ventricular function.
Also there are some advantages for patients with disorders in intraventricular impulse conduction and allows the re-establishment of the normal intraventricular activation sequency.
Other advantage is that in patients who suffered from heart failure with blockage in its left branch, allows me to apply well-known advantages of re-synchronization through using only one catheter, so as to obtain the electric alternative circuit procedure that we herewith call EB Electric Bypass.
As already known, traditional ventricular stimulation in the apex of right ventricle (RV) has shown along the years, great trust as regards its permanence, control of the cardiac frequency and ease for its introduction. However, day by day it has been proved that regardless the fact that it keeps atrio-ventricular synchrony through stimulation of both chambers, results are far away of causing a real phyisological synchrony. Right ventricular stimulation on apex of RV generates a pattern of electric activity, asynchronic in itself and therefore contraction and asynchronic left ventricular contraction.
On the other hand, stimulation in the apex of the RV can lead to non-homogenous left ventricular contraction, myofibril erradication, and disorders of myocardic perfussion. These disorders cause an increase in the morbidity and mortality of these patients, therefore leading from several years ago to look for other places of unique and simultaneous stimulation in order to improve electric and hemodynamic parameters of constant stimulation.
In the illustrative examples attached to the present invention its significant usefulness is shown, in presence of left ventricular dysfunction with dual-chamber (AV) pacing, resynchronizing its activity with only one catheter in RV septum, without the need of special electrophysiologist training, as seen in FIG. 9. Therefore the potential outbreak in the use of the pacemaker of my invention for constant stimulation is shown.